Light and scanning electron microscopic study on the structure of the lingual papillae of the feathertail glider (Acrobates pygmeus, Burramyidae, Marsupialia)

Abstract

The structure of the tongue of the marsupial feathertail glider (Acrobates pygmeus) was observed under a light and scanning electron microscope. The elongated tongue with a sharpened apex is ca. 10 mm in length. Only the posterior half of the tongue is attached to the bottom of the oral cavity by the frenulum, which facilitates considerable mobility of the anterior free part of the tongue. On the dorsal surface of the tongue, three types of lingual papillae were distinguished, that is, mechanical filiform papillae and gustatory fungiform and vallate papillae. The arrangement, shape, and size of filiform papillae and the direction of their keratinized processes change depending on the part of the tongue, so that the surface of the apex and the body of the tongue resembles a brush adapted to effective holding of semiliquid food and collection of pollen. The fungiform papillae have a single taste bud and are uniformly scattered between filiform papillae only on the anterior half of the tongue. On the smooth root of the tongue, three oval vallate papillae are arranged in the form of a triangle, similarly as it is the case in other marsupials. The posterior biggest vallate papilla is oriented perpendicularly to the smaller anterior papillae. The results of the study on the feathertail glider show that the special arrangement of lingual papillae is strongly adapted to feeding behavior of this nectar-eating and frugivorous animal.